1. Field of the Invention
The present invention relates to a character printing apparatus having a printing function or a transferring function. The present invention is preferably applicable, in particular, to a tape printing apparatus, a stamp producing apparatus or the like having a limitation (e.g., a limitation of several lines) on the number of lines of the character string to be printed or transferred.
2. Discussion of the Related Art
A tape printing apparatus, which is one of character printing apparatuses, is designed to facilitate preparation of a label originated by the user which is to be attached on a spine cover of a file or the like.
A conventional tape printing apparatus has a key which is provided on an operation panel and adapted to input characters so that a desired character string can be previously inputted by operating the key.
Also, the conventional tape printing apparatus has a tape feeding mechanism by which a tape can be fed and discharged through a tape discharging outlet.
Further, the conventional tape printing apparatus has a printing mechanism, including a thermal head, and a tape cutting mechanism provided in this order on the path for allowing the tape to be fed.
In the tape printing apparatus, when a print instruction key is operated, control means controls the tape feeding mechanism to feed the tape at a predetermined speed, and controls the tape printing mechanism to print the previously inputted character string on the tape thus fed.
Also, when printing of the character string is completed, the control means further controls the tape feeding mechanism to vacantly feed the tape (i.e., to feed the tape without performing printing on the tape) until a portion of the tape on which printing is completed is entirely positioned outside the tape printing apparatus, then causes the feeding of the tape to be stopped.
After the feeding of the tape is stopped, the tape portion associated with printing of the character string is cut off by the user with the tape cutting mechanism or by the action of an automatic tape cutting mechanism.
Thus, a label originated by the user having thereon a desired character string can be obtained.
In the tape printing apparatus which performs the above-mentioned processing, when printing is designated by operating the print instruction key, various types of print attributes are determined, and the printing of the character string is performed on the basis of the print attributes thus determined.
As one of the print attributes, a line-gap dot number can be mentioned. The line-gap dot number represents the number of dots allocated to the spacing (gap) formed between consecutive two lines of the character string. In the tape printing apparatus, the user find it more difficult to determine the line-gap dot number than in the other character printing apparatuses having a printing function, such as a word processor.
More specifically, in a word processor, it is common that the character sizes on the respective lines are the same, and that the dimensions of sheets serving as a print medium are also the same. Accordingly, the line-gap dot number can be obtained by a simple method of subtracting a specified character size from a specified line pitch. The term "line pitch" as used herein refers to the distance between the base lines of consecutive two lines of the character string.
In contrast, in the tape printing apparatus, since the print medium is a label (tape), it often happens that different character sizes are specified with respect to the respective lines of the character string. Also, the tape width varies with the tape serving as the print medium. Consequently, in the tape printing apparatus, it is difficult to determine the line-gap dot number by the above-mentioned simple method.
To solve the above-mentioned problems, in the conventional tape printing apparatus, as a way of deciding the line-gap dot number, a technique that there is provided a line-gap dot-number extracting table and the line-gap dot number is determined by accessing the table. The line-gap dot-number extracting table stores line-gap dot numbers each of which is related to the tape width of the loaded tape, the number of lines of the input character string and the character sizes of the respective lines of the input character string. The line-gap dot number is extracted by employing the tape width, the number of lines and the character sizes as keys (clues).
The line-gap dot-number extracting table also stores an external-line-gap dot number, and the external-line-gap dot number is also determined by using the line-gap dot-number extracting table in the same way as the line-gap dot number. The external-line-gap dot number represents the number of dots to be allocated to an external gap. The external line gap is formed between the upper edge of the tape and the firstline of the character string. The external line gap is also formed between the lower edge of the tape and the last line of the character string.
However, the way of determining the line-gap dot number and the external-line-gap dot number by using the line-gap dot-number extracting table has a problem that the table fails to meet the requirement to reduce the total amount of the ROM to a small value since the number of conditions of determining the line-gap dot number and the external-line-gap dot number and accordingly data amount of the table are increased.
More specifically, with the widespread of tape printing apparatuses, the users have strongly demanded a tape printing apparatus which can treat various tape widths. To meet such a demand, tape printing apparatuses capable of treating various tape widths (e.g., six kinds of tape widths) have actually become commercially available. In such tape printing apparatuses, the maximum of the tape width is set to a value larger than the maximum tape width allowed by conventional tape printing apparatuses, and accordingly the number of the character sizes is inevitably increased. Also, when the tape width is set to the maximum or a near value, the number of lines of a character string allowed to be contained in the tape (label) is increased. Consequently, the number of combinations of the character sizes is also increased.
This implies that the number of conditions for determining the line-gap dot number and the external-line-gap dot number is increased, i.e., that the number of combinations of the parameters is increased. As a result, the amount of data constituting the line-gap dot-number extracting table becomes extremely large, and accordingly the data of the line-gap dot-number extracting table inevitably occupies a large part of the memory capacity of the ROM.
On the other hand, in order to meet requirement for compactness and low cost of the apparatus, a small-size character printing apparatus, such as a tape printing apparatus, must have a smaller ROM's memory capacity than a large-size character printing apparatus, such as a word processor.
Accordingly, if a large part of the ROM's memory capacity is allocated to the line-gap dot-number extracting table, the other parts of the ROM's memory capacity is taken up by the table, which unfavorably causes deterioration of functions related to the data stored in the taken-up area.
As a way of solving the above-described problem, a technique of increasing the amount of the ROM's memory capacity can be employed. However, when this technique is employed, it is necessary to provide a ROM having large memory capacity which is very expensive. Thus, increase in the amount of the ROM's memory itself causes the increase in the cost of the apparatus. Further, if more memory capacity is needed, a plurality of such expensive ROMs must be provided, and accordingly the requirement for compactness and low cost of the apparatus cannot be satisfied.
Under the above-mentioned circumstances, there has been a strong need for a character printing apparatus in which the amount of data for determining the line-gap dot number and the external-line-gap dot number to be previously provided in the apparatus is reduced to a small value.
The above-described problems also arise in a stamp producing apparatus used for producing a stamp.